Advanced Thermoelectric Materials

SEM image of cross-section of Si/Ge functionally- graded nanocomposite. The arrow points to the direction of EDS line-scan.

Solid-state thermoelectric refrigeration and power generation devices have many attractive features compared with other methods, such as long life, no moving parts, no emissions of toxic gases, light weight, low maintenance, and high reliability. However, their use has been limited by the relatively low energy conversion efficiency of present thermoelectric devices. The energy conversion efficiency is mainly determined by thermoelectric figure-of-merit: Z=S2s/k, where S is the Seebeck coefficient, s is the electrical conductivity, and k is the thermal conductivity. The dimensionless form, ZT is commonly used. Researchers at Dr. Yang’s lab are developing two-component nanocomposite materials with high thermoelectric figure-of-merit ZT that are amendable to large-scale production.